A long-term controlled drug-delivery with anionic beta cyclodextrin complex in layer-by-layer coating for percutaneous implants devices

Construction and Properties of O/W Liquid Crystal Nanoemulsion

Liquid crystal emulsion is a new type of emulsion, in which the emulsifier molecules are located at the oil/water (O/W) interface and form a long-range ordered and short-range disordered lamellar liquid crystal. The lamellar liquid crystal formed by the emulsifier is similar to the skin stratum corneum lipid structure, which enables it to have a broad application prospect in the fields of cosmetics, pharmaceuticals, etc. In this work, a liquid crystal nanoemulsion was obtained by passing a liquid crystal emulsion stabilized by hydrogenated lecithin and phytosterol combination through a microfluidizer. The microstructure of the prepared liquid crystal nanoemulsion was investigated experimentally by dynamic light scattering, transmission electron microscopy, and small-angle X-ray scattering. The results have shown that the nanoemulsion inherited the liquid crystal emulsion property, namely, the long-range ordered and short-range disordered lamellar structure still existed at the oil/water interface even though they underwent extrusion, friction, and acceleration. At the same time, the underlying mechanisms of the existence of lamellar liquid crystal between the oil phase and the water phase for the nanoemulsion were explored theoretically by molecular dynamics simulations. The simulation results elucidated that the hydrogenated lecithin and phytosterol combination improved the flexibility of the bilayer structure composed of emulsifiers. The bilayers were the basic structure units of lamellar liquid crystals, and thus, the improved flexibility of bilayers provided insurance for the existence of lamellar liquid crystals with larger curvature around the oil droplets. In addition, the applicable properties of liquid crystal nanoemulsion were studied, and the results have shown that the liquid crystal nanoemulsion presented better slow-release and moisturizing properties than traditional nanoemulsions due to the existence of multilayers between oil and water phases. This work not only provides necessary information for the development and effective application of liquid crystal emulsions but also is helpful for in-depth understanding the inner properties of lamellar liquid crystal at molecular level.

Biocompatibility and inflammatory response of silver tungstate, silver molybdate, and silver vanadate microcrystals

Silver tungstate (α-Ag2WO4), silver molybdate (β-Ag2MoO4), and silver vanadate (α-AgVO3) microcrystals have shown interesting antimicrobial properties. However, their biocompatibility is not yet fully understood. Cytotoxicity and the inflammatory response of silver-containing microcrystals were analyzed in THP-1 and THP-1 differentiated as macrophage-like cells, with the alamarBlue™ assay, flow cytometry, confocal microscopy, and ELISA. The present investigation also evaluated redox signaling and the production of cytokines (TNFα, IL-1β, IL-6, and IL-8) and matrix metalloproteinases (MMP-8 and -9). The results showed that α-AgVO3 (3.9 μg/mL) did not affect cell viability (p > 0.05). α-Ag2WO4 (7.81 μg/mL), β-Ag2MoO4 (15.62 μg/mL), and α-AgVO3 (15.62 μg/mL) slightly decreased cell viability (p ≤ 0.003). All silver-containing microcrystals induced the production of O2 - and this effect was mitigated by Reactive Oxygen Species (ROS) scavenger and N-acetylcysteine (NAC). TNFα, IL-6 and IL-1β were not detected in THP-1 cells, while their production was either lower (p ≤ 0.0321) or similar to the control group (p ≥ 0.1048) for macrophage-like cells. The production of IL-8 by both cellular phenotypes was similar to the control group (p ≥ 0.3570). The release of MMP-8 was not detected in any condition in THP-1 cells. Although MMP-9 was released by THP-1 cells exposed to α-AgVO3 (3.9 μg/mL), no significant difference was found with control (p = 0.7). Regarding macrophage-like cells, the release of MMP-8 and -9 decreased in the presence of all microcrystals (p ≤ 0.010). Overall, the present work shows a promising biocompatibility profile of, α-Ag2WO4, β-Ag2MoO4, and α-AgVO3 microcrystals.

Biomaterial engineering surface to control polymicrobial dental implant-related infections: focusing on disease modulating factors and coatings development

INTRODUCTION

Peri-implantitis is the leading cause of dental implant loss and is initiated by a polymicrobial dysbiotic biofilm formation on the implant surface. The destruction of peri-implant tissue by the host immune response and the low effectiveness of surgical or non-surgical treatments highlight the need for new strategies to prevent, modulate and/or eliminate biofilm formation on the implant surface. Currently, several surface modifications have been proposed using biomolecules, ions, antimicrobial agents, and topography alterations.

AREAS COVERED

Initially, this review provides an overview of the etiopathogenesis and host- and material-dependent modulating factors of peri-implant disease. In addition, a critical discussion about the antimicrobial surface modification mechanisms and techniques employed to modify the titanium implant material is provided. Finally, we also considered the future perspectives on the development of antimicrobial surfaces to narrow the bridge between idea and product and favor the clinical application possibility.

EXPERT OPINION

Antimicrobial surface modifications have demonstrated effective results; however, there is no consensus about the best modification strategy and in-depth information on the safety and longevity of the antimicrobial effect. Modified surfaces display recurring challenges such as short-term effectiveness, the burst release of drugs, cytotoxicity, and lack of reusability. Stimulus-responsive surfaces seem to be a promising strategy for a controlled and precise antimicrobial effect, and future research should focus on this technology and study it from models that better mimic clinical conditions.

The Role of Cyclodextrin in the Construction of Nanoplatforms: From Structure, Function and Application Perspectives

Cyclodextrins (CyDs) in nano drug delivery systems have received much attention in pursuit of good compatibility, negligible toxicity, and improved pharmacokinetics of drugs. Their unique internal cavity has widened the application of CyDs in drug delivery based on its advantages. Besides this, the polyhydroxy structure has further extended the functions of CyDs by inter- and intramolecular interactions and chemical modification. Furthermore, the versatile functions of the complex contribute to alteration of the physicochemical characteristics of the drugs, significant therapeutic promise, a stimulus-responsive switch, a self-assembly capability, and fiber formation. This review attempts to list recent interesting strategies regarding CyDs and discusses their roles in nanoplatforms, and may act as a guideline for developing novel nanoplatforms. Future perspectives on the construction of CyD-based nanoplatforms are also discussed at the end of this review, which may provide possible direction for the construction of more rational and cost-effective delivery vehicles.

Ultrasound-assisted synthesis of MIL-88(Fe) conjugated starch-Fe3O4 nanocomposite: A safe antibacterial carrier for controlled release of tetracycline

A constructing antibiotic carrier with a sustained release profile is a promising method to stop long-term bacterial infection, which is of ideal interest in different biomedical fields. To end this, the present study aims to design a novel carrier based on the modification of biopolymeric starch for the rising possible interaction between carrier and antibiotic agent. We established an in-situ ultrasound-assisted method was applied to grow and create MIL-88(Fe) framework in the structure of magnetic polysaccharide (i.e., St/Fe₃O₄) synthesized by precipitation method resulting in St/Fe₃O₄/MIL-88(Fe) nanocomposite. It was loaded with a high amount of Tetracycline (TC) through its immersion into the TC aqueous solution. The release profile of TC-loaded St/Fe₃O₄/MIL-88(Fe) displays a lower initial burst release (about 26 % after 12 h) and followed by a controlled and sustained release (about 73 % up to 168 h) in the simulated physiological environment at pH 7.4. The in vitro cytotoxicity showed good cytocompatibility against Human skin fibroblast (HFF-1) cells. TC-loaded St/Fe₃O₄/MIL-88(Fe) showed higher antibacterial activity against both S. aureus and E. coli with the MIC value of 64 and 128 μg·mL^-1, respectively.

Cyclodextrins as eminent constituents in nanoarchitectonics for drug delivery systems

Cyclodextrins have been widely employed for drug delivery systems (DDSs) in which drugs are selectively delivered to a target site in the body. Recent interest has been focused on the construction of cyclodextrin-based nanoarchitectures that show sophisticated DDS functions. These nanoarchitectures are precisely fabricated based on three important features of cyclodextrins, namely (1) the preorganized three-dimensional molecular structure of nanometer size, (2) the easy chemical modification to introduce functional groups, and (3) the formation of dynamic inclusion complexes with various guests in water. With the use of photoirradiation, drugs are released from cyclodextrin-based nanoarchitectures at designated timing. Alternatively, therapeutic nucleic acids are stably protected in the nanoarchitectures and delivered to the target site. The efficient delivery of the CRISPR-Cas9 system for gene editing was also successful. Even more complicated nanoarchitectures can be designed for sophisticated DDSs. Cyclodextrin-based nanoarchitectures are highly promising for future applications in medicine, pharmaceutics, and other relevant fields.

An Overview of the Supramolecular Systems for Gene and Drug Delivery in Tissue Regeneration

Tissue regeneration is a prominent area of research, developing biomaterials aimed to be tunable, mechanistic scaffolds that mimic the physiological environment of the tissue. These biomaterials are projected to effectively possess similar chemical and biological properties, while at the same time are required to be safely and quickly degradable in the body once the desired restoration is achieved. Supramolecular systems composed of reversible, non-covalently connected, self-assembly units that respond to biological stimuli and signal cells have efficiently been developed as preferred biomaterials. Their biocompatibility and the ability to engineer the functionality have led to promising results in regenerative therapy. This review was intended to illuminate those who wish to envisage the niche translational research in regenerative therapy by summarizing the various explored types, chemistry, mechanisms, stimuli receptivity, and other advancements of supramolecular systems.

Race for Applicable Antimicrobial Dental Implant Surfaces to Fight Biofilm-Related Disease: Advancing in Laboratorial Studies vs Stagnation in Clinical Application

Across years, potential strategies to fight peri-implantitis have been notoriously explored through the antimicrobial coating implant surfaces capable of interfering with the bacterial adhesion process. However, although experimental studies have significantly advanced, no product has been marketed so far. For science to reach the society, the commercialization of research outcomes is necessary to provide real advancement in the biomedical field. Therefore, the aim of this study was to investigate the challenges involved in the development of antimicrobial dental implant surfaces to fight peri-implantitis, through a systematic search. Research articles reporting antimicrobial dental implant surfaces were identified by searching PubMed, Scopus, Web of Science, The Cochrane Library, Embase, and System of Information on Grey Literature in Europe, between 2008 and 2020. A total of 1778 studies were included for quality assessment and the review. An impressive number of 1655 articles (93,1%) comprised in vitro studies, whereas 123 articles refer to in vivo investigations. From those 123, 102 refer to animal studies and only 21 articles were published on the clinical performance of antibacterial dental implant surfaces. The purpose of animal studies is to test how safe and effective new treatments are before they are tested in people. Therefore, the discrepancy between the number of published studies clearly reveals that preclinical investigations still come up against several challenges to overcome before moving forward to a clinical setting. Additionally, researchers need to recognize that the complex journey from lab to market requires more than a great idea and resources to develop a commercial invention; research teams must possess the skills necessary to commercialize an invention.

Bioactive Coatings on Titanium: A Review on Hydroxylation, Self-Assembled Monolayers (SAMs) and Surface Modification Strategies

Titanium (Ti) and its alloys have been demonstrated over the last decades to play an important role as inert materials in the field of orthopedic and dental implants. Nevertheless, with the widespread use of Ti, implant-associated rejection issues have arisen. To overcome these problems, antibacterial properties, fast and adequate osseointegration and long-term stability are essential features. Indeed, surface modification is currently presented as a versatile strategy for developing Ti coatings with all these challenging requirements and achieve a successful performance of the implant. Numerous approaches have been investigated to obtain stable and well-organized Ti coatings that promote the tailoring of surface chemical functionalization regardless of the geometry and shape of the implant. However, among all the approaches available in the literature to functionalize the Ti surface, a promising strategy is the combination of surface pre-activation treatments typically followed by the development of intermediate anchoring layers (self-assembled monolayers, SAMs) that serve as the supporting linkage of a final active layer. Therefore, this paper aims to review the latest approaches in the biomedical area to obtain bioactive coatings onto Ti surfaces with a special focus on (i) the most employed methods for Ti surface hydroxylation, (ii) SAMs-mediated active coatings development, and (iii) the latest advances in active agent immobilization and polymeric coatings for controlled release on Ti surfaces.

Analytical Techniques for the Characterization of Bioactive Coatings for Orthopaedic Implants

The development of bioactive coatings for orthopedic implants has been of great interest in recent years in order to achieve both early- and long-term osseointegration. Numerous bioactive materials have been investigated for this purpose, along with loading coatings with therapeutic agents (active compounds) that are released into the surrounding media in a controlled manner after surgery. This review initially focuses on the importance and usefulness of characterization techniques for bioactive coatings, allowing the detailed evaluation of coating properties and further improvements. Various advanced analytical techniques that have been used to characterize the structure, interactions, and morphology of the designed bioactive coatings are comprehensively described by means of time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), 3D tomography, quartz crystal microbalance (QCM), coating adhesion, and contact angle (CA) measurements. Secondly, the design of controlled-release systems, the determination of drug release kinetics, and recent advances in drug release from bioactive coatings are addressed as the evaluation thereof is crucial for improving the synthesis parameters in designing optimal bioactive coatings.

Antibacterial nanofibers of pullulan/tetracycline-cyclodextrin inclusion complexes for Fast-Disintegrating oral drug delivery

Tetracycline is a widely used antibiotic suffering from poor water solubility and low bioavailability. Here, hydroxypropyl-beta-cyclodextrin (HPβCD) was used to form inclusion complexes (IC) of tetracycline with 2:1 M ratio (CD:drug). Then, tetracycline-HPβCD-IC was mixed with pullulan- a non-toxic, water-soluble biopolymer - to form nanofibrous webs via electrospinning. The electrospinning of pullulan/tetracycline-HPβCD-IC was yielded into defect-free nanofibers collected in the form of a self-standing and flexible material with the loading capacity of ∼ 7.7 % (w/w). Pullulan/tetracycline nanofibers was also generated as control sample having the same drug loading. Tetracycline was found in the amorphous state in case of pullulan/tetracycline-HPβCD nanofibers due to inclusion complexation. Through inclusion complexation with HPβCD, enhanced aqueous solubility and faster release profile were provided for pullulan/tetracycline-HPβCD-IC nanofibers compared to pullulan/tetracycline one. Additionally, pullulan/tetracycline-HPβCD-IC nanofibers readily disintegrated when wetted with artificial saliva while pullulan/tetracycline nanofibers were not completely absorbed by the same simulate environment. Electrospun nanofibers showed promising antibacterial activity against both gram-positive and gram-negative bacteria. Briefly, our findings indicated that pullulan/tetracycline-HPβCD-IC nanofibers could be an attractive material as orally fast disintegrating drug delivery system for the desired antibiotic treatment thanks to its promising physicochemical and antibacterial properties.

Polyelectrolyte Multilayers: An Overview on Fabrication, Properties, and Biomedical and Environmental Applications

Polyelectrolyte multilayers are versatile materials that are used in a large number of domains, including biomedical and environmental applications. The fabrication of polyelectrolyte multilayers using the layer-by-layer technique is one of the simplest methods to obtain composite functional materials. The properties of the final material can be easily tuned by changing the deposition conditions and the used building blocks. This review presents the main characteristics of polyelectrolyte multilayers, the fabrication methods currently used, and the factors influencing the layer-by-layer assembly of polyelectrolytes. The last section of this paper presents some of the most important applications of polyelectrolyte multilayers, with a special focus on biomedical and environmental applications.

Ultrasound-assisted synthesis of MIL-88(Fe) coordinated to carboxymethyl cellulose fibers: A safe carrier for highly sustained release of tetracycline

For stopping long-time harmful bacterial infection, designing a drug carrier with a highly prolonged release profile is a promising approach that is of interest to different biomedical areas. The subject of this work is to synthesis a novel carrier system through coordination of MIL-88(Fe) to carboxymethyl cellulose (CMC) for enhancing interaction between drug and carrier. We established an ultrasound-assisted synthetic method for in situ synthesis of MIL-88(Fe) in the presence of CMC resulting in CMC/MIL-88(Fe) composite. The CMC/MIL-88(Fe) was loaded with a high amount of Tetracycline (TC) by immersion of carrier to the TC aqueous solution. The release profile in the simulated physiological conditions, pH 7.4, revealed a low initial burst release followed by a sustained and prolonged release over 384 h. The in vitro cytotoxicity of CMC/MIL-88(Fe) against Human skin fibroblast (HFF-1) cells was calculated by MTT assay and showed a good cytocompatibility. The antibacterial activity was found for TC-loaded CMC/MIL-88(Fe) toward both E. coli and S. aureus with MIC 64 mg·ml^-1.